Display screens are generally arranged in public places like a bus, a subway, a high-speed railway, a building, an elevator, for playing specific programs, advertisements, propagandas. These display apparatuses are subject to a high fault rate due to the complicated service environment. In order to timely detect the fault, a color sensor is currently applied to determine display faults in the display screen. In a specific detecting method, the display screen is made to display a predefined monochromatic image, e.g., a red image, a green image, or a blue image. The color sensor detects the color of images displayed by the display screen, to obtain components of red, green, and blue (RGB) primary colors in the detected color in images, for determining whether there is a display fault in the display screen.
However, in the above process for determining the fault, there is a difference between the results detected by the color sensor and the actual values due to the effect of ambient light. In particularly, in case the ambient light is strong, the difference increases, thus leading to misjudgment.